Process for removing ash and mineral components from dextrose liquor



United States Patent Office 3,276,908 Patented Oct. 4, 1966 3 276 908 PROCESS FOR REMO "IN G ASH AND MINERAL COMPONENTS FROM DEXTROSE LIQUOR Leo R. Idaszak, Oak Lawn, Ill., assignor to Corn Products which in passing through the electrodialyzer cells becomes enriched in ash, the other of which becomes depleted of ash. The ash-enriched sub-stream (herein termed the concentrate stream) is conducted back to the main dextrose stream or processed to make a salable ggigpany, New York, a corporation of Dela 5 product and the second sub-stream of reduced ash content No Drawing, Filed J 19 4, 33 ,034 (herein termed the product stream) is processed to pro- 2 Claims. (Cl. 127-40) duce a dextrose syrup of low ash and mineral content.

The process of my invention is illustrated by the fol- This invention relates to the manufacture of dextrose lowin examp1e liquors. More particularly, this invention relates to the 10 A Str f a crystallizer supply liquor obtained from use of electrodialysis to remove ash and mineral comthe acid-enzyme conversion of starch and having a Brix ponents from dextrose liquors. of 57 (30 B.) was divided into two streams and passed The electrodialysis of aqueous solutions is effected in through an electrodialyzer cell. The dextrose liquor had multi-membrane demineralizers having alternating dilutan iron content of 15 ppm. D.B. before electrodialysis ing and concentrating chambers with spaced alternating and the product stream after electrodialysis had an iron cation and anion permselective membranes therebetween content of less than 4 p.p.m. The product stream was defining the diluting and concentrating solutions, respecpassed to evaporators for processing in the usual manner tively. to make a low-ash dextrose and the concentrate stream When solutions of organic substances are subjected to was returned to the main dextrose syrup stream. electrodialysis, Water as a dilute electrolyte (0.02 N My process is applicable to any ash-containing dextrose NaCl) is commonly used as the concentrate stream. liquor (e.g. first or second greens, crystallizer supply liq- This method has three major disadvantages. Valuable uor or blends of liquors) which is free of insoluble matenon-ionic components in the dialysate (product) stream rials which would tend to plug the small solution passages such as sugar, difiuse through the membranes into the in the electrodialysis unit. It is preferable to use liquors concentrate stream because of concentration gradients. having a concentration of approximately 55% D8. or This diffusion represents a loss of valuable material. A B. since this concentration results in the highest second disadvantage of this method is that water is transdeashing rate, thus permitting a given amount of product ferred from the concentrate stream to the dialysate stream to be processed with the smallest amount of electrobecause of the concentration gradient. This water trans- 30 dialysis equipment. It is advisable to avoid extremely fer is a true dilution and is not a result of decreased high concentrations; e.g. at 37 B. there are problems in dry substance concentration because of difiusional dry physically getting material through the electrodialysis substance losses. This water dilution represents an addiunit because of viscosity problems. tional operating expense in terms of evaporating costs. Table I shows that the percent of deashing increases The third disadvantage of the conventional method of with increasing voltage and decreasing dry substance. operating an electrodialysis process is that internal leak- Although the percent deashing increases with decreasing age within the electrodialysis unit, which can occur accidry substance, the actual ash removal, i.e., pounds of ash dentally, could result in additional loss of valuable materemoved, is less because the total ash present decreases rial and/or additional water dilution. with decreasing dry substance.

TABLE I Deashing of sugar liquor Cell Pair, volts Dry 5.05 3.28 1.54 Substance, percent Average Ash Average Ash Average Ash Deashing, Removed, Deashing, Removed, Deashing, Removed,

percent 1b. percent lb. percent lb.

55 89. 3 0. 0207 79. 3 0. 0184 67. s 0. 0157 Liquor-Liquor 40 89. 9 0. 014 80. 8 0. 0135 85. 1 0. 0117 20 99 0. 00711 94. 9 0. 00683 92. 4 0. 00665 Liquor-Water 88. 2 0. 0204 81. 8 0. 0190 78. 6 0. 0182 Based on a supply volume of 1 gallon, ash content 0.4 percent D.B.

I have eliminated the three disadvantages listed above by using the same liquid on both sides of the electrodialysis membrane. I have referred to this as the liquorliquor system to distinguish from the conventional liquorwater system. According to my method, a given process stream is divided into two basic component streams for electrodialysisthe disalysate stream and the concentrate stream. Electrical energy is used to transfer ionic ash and mineral components from the dialysate stream to the concentrate stream. Since I am concerned primarily with removing ash from dextrose liquors, I have referred to the dialysate stream as the product stream.

The process of my invention comprises taking a tap or branch stream from a main dextrose liquor stream, splitting this branch stream into two sub-streams, one of The operating temperature of the electrodialysis unit is governed by the temperature limitations of the membranes. At the present time, the most satisfactory temperatures for operating commercially available membranes is about F.

I have also found that by subjecting mother liquor from a dextrose crystallization process to electrodialysis, two grades of hydrol may be produced. Hydr'ol from an acidenzyme conversion of starch to dextrose contains approximately 2 percent ash and hydrol from the conventional acid process for hydrolysis of starch to dextrose contains up to 8 percent ash. By subjecting the hydrol to electrodialysis, a low ash dextrose product may be produced (less than 0.5% ash) and the concentrate stream may be processed in accordance with the usual practice in the crystalline dextrose process to produce a product having an ash content of about 7%.

Use of electrodialysis before refining may improve refining efliciency with corresponding decrease in amount of refining agent used. Althoughelectrodialysis is not considered a refining operation, there is an improvement in the quality (color, clarity, protein content) of the product stream. This increase in product stream quality is accompanied by a decrease in the concentrate stream quality.

By using the dextrose liquor on both sides of the electrodialysis membrane in accordance with the process of my invention, there is no transfer of water or dextrose through the membranes. This is a great improvement over the usual liquor-water system wherein there is a transfer of dextrose when applied to dextrose liquors and water as shown in Table H.

TABLE II Summary of dextrose and water transfer All 30 B. liquors used for d'ialysate stream, water (0.02 N NaOlused for concentrate stream.

I claim: 1. A process for removing ash and mineral components from dextrose liquor comprising dividing a dextrose liqnor having a concentration of about dry substance into two streams, passing one of said streams through an electrodialyzer cell on one side of a semi-permeable electrodialysis membrane and simultaneously passing the other stream on the other side of the membrane, said membrane permitting only. the passage of ions from one stream to the other, recovering the ion-depleted stream as a dextrose product stream depleted of ash and removing the other dextrose stream enriched in ash for further processing.

2. A process forremcving ash and mineral components from dextrose liquor comprising dividing the mother liquor obtained from a dextrose crystallization process and having a dry substance concentration of about 55% and an ash content, dry basis, of about 0.5% to about 8.0%, into two streams, passing one of said streams through an electrodialyzer cell on one side of a semipermeable electrodialysis membrane and simultaneously passing the other stream on the other side of the membrane, said membrane permitting only the passage of ions from one stream to the other, removing the resulting dextrose product stream as a low ash liquid dextrose product, and removing the other dextrose stream enriched in ash for further processing.

References Cited by the Examiner UNITED STATES PATENTS 2,393,095 1/1946 Fetzer l27-40 2,860,091 11/1958 Rosenberg 204 X FOREIGN PATENTS 302,375 12/1928 Great Britain.

MORRIS O. WOLK, Primary Examiner.

MICHAEL E. ROGERS, Examiner. 

1. A PROCESS FOR REMOVING ASH AND MINERAL COMPONENTS FROM DEXTROSE LIQUOR COMPRISING DIVIDING A DEXTROSE LIQUOR HAVING A CONCENTRATION OF ABOUT 55% DRY SUBSTANCE INTO TWO STREAMS, PASSING ONE OF SAID STREAMS THROUGH AN ELECTRODIALYZER CELL ON ONE SIDE OF A SEMI-PERMEABLE ELECTRODIALYSIS MEMBRANE AND SIMULTANEOUSLY PASSING THE OTHER STREAM ON THE OTHER SIDE OF THE MEMBRANE, SAID MEMBRANE PERMITTING ONLY THE PASSAGE OF IONS FROM ONE STREAM TO THE OTHER, RECOVERING THE ION-DEPLETED STREAM AS A DEXTROSE PRODUCT STREAM DEPLETED OF ASH AND REMOVING THE OTHER DEXTROSE STREAM ENRICHED IN ASH FOR FURTHER PROCESSING. 